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https://bugs.gentoo.org/566792
From 00837731d254908a841d69298a4f9f077babaf24 Mon Sep 17 00:00:00 2001
From: Stefan Weil <sw@weilnetz.de>
Date: Fri, 20 Nov 2015 08:42:33 +0100
Subject: [PATCH] eepro100: Prevent two endless loops
http://lists.nongnu.org/archive/html/qemu-devel/2015-11/msg04592.html
shows an example how an endless loop in function action_command can
be achieved.
During my code review, I noticed a 2nd case which can result in an
endless loop.
Reported-by: Qinghao Tang <luodalongde@gmail.com>
Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
hw/net/eepro100.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/hw/net/eepro100.c b/hw/net/eepro100.c
index 60333b7..685a478 100644
--- a/hw/net/eepro100.c
+++ b/hw/net/eepro100.c
@@ -774,6 +774,11 @@ static void tx_command(EEPRO100State *s)
#if 0
uint16_t tx_buffer_el = lduw_le_pci_dma(&s->dev, tbd_address + 6);
#endif
+ if (tx_buffer_size == 0) {
+ /* Prevent an endless loop. */
+ logout("loop in %s:%u\n", __FILE__, __LINE__);
+ break;
+ }
tbd_address += 8;
TRACE(RXTX, logout
("TBD (simplified mode): buffer address 0x%08x, size 0x%04x\n",
@@ -855,6 +860,10 @@ static void set_multicast_list(EEPRO100State *s)
static void action_command(EEPRO100State *s)
{
+ /* The loop below won't stop if it gets special handcrafted data.
+ Therefore we limit the number of iterations. */
+ unsigned max_loop_count = 16;
+
for (;;) {
bool bit_el;
bool bit_s;
@@ -870,6 +879,13 @@ static void action_command(EEPRO100State *s)
#if 0
bool bit_sf = ((s->tx.command & COMMAND_SF) != 0);
#endif
+
+ if (max_loop_count-- == 0) {
+ /* Prevent an endless loop. */
+ logout("loop in %s:%u\n", __FILE__, __LINE__);
+ break;
+ }
+
s->cu_offset = s->tx.link;
TRACE(OTHER,
logout("val=(cu start), status=0x%04x, command=0x%04x, link=0x%08x\n",
--
2.6.2
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